CN1004085B - A kind of concrete pavement construction method - Google Patents

Abstract

The invention belongs to the technical field of concrete pavement. The present invention paves the vibrating concrete mixed with fly ash on the base layer, and immediately pours the low-plasticity concrete or the low-plasticity concrete mixed with fly ash without plastering the surface after being vibrated and rolled into shape. The invention utilizes the strengths of the two concrete construction techniques, saves a large amount of cement, reduces the cost of the road surface, and improves the smoothness and service life of the road surface. The invention is applicable to roads of various grades and roads in various climate regions.

Description

Concrete pavement construction method

The present invention belongs to the field of concrete paving technology.

The vibration rolling concrete (vibration rolling concrete) is a new process for compacting and forming dry and hard concrete by using a vibration road roller developed in the middle of seventies abroad. This concrete is useful as a surface layer, but has not been widely used because the surface of the pavement is not easily leveled. According to the journal of Concrete restriction of 3 months in 1986, there is a title "State of the art: the patent with roller compacted concrete "reported that canada used a 6.5 inch thick shake-rolled concrete for the lower layer and a 1.5 inch thick asphalt concrete for the upper layer. Obviously, the use of asphalt concrete as the upper layer has shorter service life than cement concrete, and the price of asphalt is greatly increased, so that the cost of the asphalt pavement is close to or even higher than that of the cement pavement.

The invention aims to solve the problem of high consumption of plastic concrete cement, solve the problem of poor flatness of a vibration-milled concrete pavement, and simultaneously provide a concrete pavement construction method for further improving the pavement quality and reducing the pavement cost. The method is to pave 2/3 thick vibration-milled concrete doped with fly ash on a base layer to serve as a lower surface layer so as to reduce the using amount of cement and improve the quality of a road surface, and then pave 1/3 thick low-plasticity concrete or the fly ash-doped low-plasticity concrete to serve as an upper surface layer so as to improve the flatness of the road surface.

The concrete road surface is vibrated and ground by adopting the low-plasticity concrete or the fly ash-doped low-plasticity concrete on the upper surface layer and the fly ash-doped low-plasticity concrete on the lower surface layer, the upper layer and the lower layer are well combined, no obvious interface exists, and the damaged surface is not on the contact surface of the upper layer and the lower layer when a strength test is performed. The compactness, early and later strength and crack resistance of the pavement concrete are improved, the shrinkage, elastic modulus and brittleness are correspondingly reduced, the flatness and service life of the pavement are also improved, the cement consumption is reduced, the cement is saved by 30 percent, and the engineering cost of the pavement is reduced by 8 to 10 percent.

The detailed construction process of the invention is as follows: paving the vibration-milled concrete mixture doped with the fly ash on a base layer (the base layer can be made of any base layer material, preferably a lime fly ash aggregate base layer, and the strength is further increased after the base layer is in contact with water because the later strength is high), and immediately pouring the low-plasticity concrete or the low-plasticity concrete doped with the fly ash without plastering after the vibration-milling forming.

The cement used for the vibration-milled concrete doped with fly ash can be portland cement, ordinary portland cement, portland slag cement and road portland cement, and preferably road portland cement. The maximum particle size of the used coarse aggregate is 40 mm, the maximum particle size of the coarse aggregate of the upper layer low-plasticity concrete is 20 mm, and the coarse aggregate can be matched in three stages or two stages according to the size of the particle size. The sand used should have a silt content of less than 5% and very fine particles passing through a 0.16 mm mesh preferably less than 15%. The additive is M-type water reducing agent of calcium lignosulphonate, the dosage of the M-type water reducing agent is 0.2 percent, the dosage of the fly ash is determined according to the grade of the cement, generally is 20 percent of the dosage of the cement, and the water is suitable for useThe basic principle of the design of the mixing proportion of the drinking water and the vibration-milled concrete doped with the fly ash is the same as that of normal concrete, and only the water consumption of people is less. They are all based on the physical and mechanical indexes of engineering requirements, select a better water-cement ratio, select a proper unit water consumption and the Weibo consistency V of the vibration-milled concrete doped with fly ash under the condition of meeting the construction working degree₈Preferably 90 to 120 seconds.

The construction process of the vibration-milled concrete doped with the fly ash comprises the following steps: firstly, mixing the vibration-rolling concrete mixture doped with the fly ash by using a mixer, then spreading, wherein the virtual spreading thickness of the mixture is about 1.35 times of the compaction thickness of the mixture, the spreading length of each time is 20-25 m, and finally performing vibration-rolling molding. The self weight of the adopted vibratory roller is 8T +/-2T, the linear pressure is more than 62.5 kg/cm, the low frequency is 1, 500-2, 000 times/min, the high frequency is 2, 500-3, 000 times/min, the amplitude of the low frequency is 0.9 mm, and the amplitude of the high frequency is 0.35-0.4 mm. When the vibrating mill is used for vibrating and rolling the paved vibrating and rolled concrete mixture doped with the fly ash, the vibrating mill transmits a vibrating wave with fixed frequency and amplitude to the mixture through the vibrating wheel and transmits the vibrating wave from top to bottom, the transmission speed and the attenuation degree along the depth are different along with the difference of the proportions of various components in the mixture and the difference of the workability of the mixture, the thicker the layer of the mixture is, the less the vibration energy obtained by the mixture at the lower part of the layer is, and the proper vibrating and rolling time or vibrating and rolling pass is needed for enabling the mixture to be uniform and compact, and the vibrating and rolling pass is calculated according to the vibrating and rolling energy formula E which is 2A (W + F/2) xNx (L/V)/(BxL). Where a is the amplitude of the vibrating wheel (single swath). W is the axial load of the vibrating wheel, F is the exciting force, V is the vibrating and grinding speed of the vibrating and grinding machine, L is the grounding length of the vibrating wheel, N is the vibration frequency, N is the vibrating and grinding number (back and forth) of the vibrating wheel, and B is the width of the vibrating wheel. In order to ensure the quality of the vibro-compaction concrete, the vibro-compaction is carried out in three steps: the mixture is statically rolled for one time (one round), and the aim is to preliminarily form the mixture so as to avoid easy forming of pits or waves during vibration rolling. And 3 times of low-frequency vibration grinding is carried out for 2-3 times, the low frequency is 1, 500-2, 000 times/minute, the vibration grinding is carried out in place on coarse aggregate particles with the particle size of 20-40 mm, and the vibration effect can be carried out until the bottom layer due to large amplitude. And finally, carrying out high-frequency vibration grinding for 2-3 times until the surface of the concrete is slightly wet. The high-frequency vibration amplitude of 2, 500-3,000 times/min is small, so that the high-frequency vibration amplitude mainly acts on a shallow layer and is suitable for fine particles in a mixture, the coarse particles are filled in gaps, the friction force of the mixture is reduced, thixotropy is facilitated, and mortar is liquefied.

After the vibration-milled concrete mixed with fly ash is formed by vibration milling, the low-plasticity concrete or the low-plasticity concrete mixed with fly ash is immediately paved without plastering, and the slump is about 1 cm. The construction process of the low-plasticity concrete is the same as that of normal concrete.

It should be emphasized that the double-layer surface layer can be cast by using concrete with the same grade, and the upper-grade concrete and the lower-grade concrete can also be used on the grade, namely, the upper layer adopts high-grade plastic concrete, and the lower layer adopts low-grade vibration-milled concrete, such as 200-grade vibration-milled concrete doped with fly ash, because the later strength is high, and the compressive strength reaches 300 kg/cm at the age of 180 days, the double-layer surface layer is 'top-bottom full-grade'.

The invention completely meets the design requirements of the pavement concrete, improves the compactness, early and later strength and crack resistance of the pavement concrete, and greatly improves the quality of the concrete. The drying shrinkage rate is low, and generally reaches (219-241) × 10 in 90 days^-6Impervious grade up to B₁₀The above. The more the fly ash is mixed, the more the concrete shrinkage is obviously reduced. The ultimate tensile value of the vibration-milled concrete doped with the fly ash is larger than that of dry lean vibration-milled concrete, so that the crack resistance of the vibration-milled concrete doped with the fly ash is superior to that of normal concrete, and the half-year strength R of No. 200 concrete is higher₁₈₀Namely 300 which reaches the 28-day strength requirement. The elastic modulus is reduced by 15-20%, so that the brittleness, which is a remarkable defect of the cement concrete, is remarkably reduced.

The invention has the advantages of two processes (namely the vibration concrete rolling and the normal concrete construction process), saving 30 percent of cement compared with the common concrete construction process, reducing about 10 percent of the road surface engineering cost, improving the road surface flatness and prolonging the service life. The method is popularized and used on highways, urban roads, airport runways and civil engineering terraces, and has obvious economic and social benefits. In addition, the invention uses the vibration grinding concrete doped with the fly ash, which opens up a new way for the comprehensive utilization of the fly ash and reduces the pollution of the fly ash to the environment. The invention is suitable for highways and highways in high and low grades and highway pavements in different climatic regions.

The first embodiment is as follows: the concrete with the thickness of 2/3 and doped with fly ash is spread on a base layer on a special line for Shanxi Shuiao coal mines and a large to double soap adding line, and after the concrete is formed by vibration rolling, the concrete with low plasticity is immediately spread without plastering. The upper and lower surface layers adopt the same-grade concrete (R)₂₈300) and the cement is saved into 2/3 of full-use vibration-milled concrete for the whole floor.

Example two: low-grade vibro-mechanical concrete (R) with lower surface layer doped with fly ash is adopted in Anhui lake₂₈200), the upper layer adopts high-grade low-plasticity concrete (R)₂₈300). The test result shows that the compressive strength of the low-grade vibro-milled concrete of the lower layer can still reach 300 kg/cm in 180 days of age²The above. The cement is saved by 28.4% on the upper and lower surface layers, which is similar to 35% for the whole layer by using the vibration-milled concrete. All the concrete pavements with the upper and lower plastic layers and the lower vibratory grinding layers are well combined, have no obvious interfaces, and damage surfaces without contact surfaces of the upper and lower layers when strength tests are carried out.

Claims (2)

1. A concrete pavement construction method includes paving 2/3 of the thickness of fly ash-added vibrated concrete on the base as the lower layer, and immediately pouring 1/3 of the thickness of low-plasticity concrete or low-plasticity concrete mixed with fly ash as the upper layer after the vibrated concrete is formed. The vibrated forming process is: first use static rolling once (one round trip), then use low-frequency vibrating at 1,500 to 2,000 times/minute for 2 to 3 times, and finally use high-frequency vibrating at 2,500 to 3,000 times/minute for 2 to 3 times. The number of vibration passes is determined by the calculated vibration energy. The fly ash-added vibrated concrete in the upper layer is made of Portland cement, ordinary Portland cement, slag Portland cement, or road cement. The coarse aggregate used in the lower layer has a maximum particle diameter of 40 mm. The fly ash-added vibrated concrete is added with a 0.2% M-type water reducer, a calcium wood sulfonate. The fly ash addition rate depends on the cement type and grade, and is 20% of the total cement content. The Vebe consistency (V8 ₎ of the fly ash-added vibrated concrete is 90 to 120 seconds. The coarse aggregate in the upper layer of low-plasticity concrete has a maximum particle diameter of 20 mm, and the fine aggregate has a particle size of less than 15% passing a 0.16 mm sieve. 2. The concrete pavement construction method according to claim 1 is characterized in that the upper layer of low-plasticity concrete or low-plasticity concrete mixed with fly ash and the lower layer of vibrated concrete mixed with fly ash can use the same concrete grade, or the upper layer of low-plasticity concrete or low-plasticity concrete mixed with fly ash uses the design grade, and the lower layer of vibrated concrete mixed with fly ash uses a lower grade.